The present invention relates to a novel fluorescent group-containing carbodiimide compound precursor and a fluorescent group-containing carbodiimide compound. More specifically, it relates to a fluorescent group-containing carbodiimide compound precursor that contains a halogen atom or a sulfonic acid group, which enables easy and efficient bonding of a fluorescent group and a method for producing it, as well as a fluorescent group-containing carbodiimide compound which has at least one group selected from a carboxyl group, a sulfo group, a phosphono group and a phospho group, which enables easy and efficient introduction of a fluorescent group into nucleic acids and proteins, a method for producing it and an analysis method utilizing it.
As methods for introducing a fluorescent substance into nucleic acids, there have been known, for example, introduction of a fluorescent substance into a nucleic acid by using a nucleotide bonded to a fluorescent substance through an enzymatic reaction and so forth (Japanese Patent Application Application Laid-open No. 6-271599), bonding of streptavidin, to which a fluorescent substance has already been bonded, to a biotin-labeled nucleic acid, a reaction of a fluorescent substance containing an amine-reactive group with a nucleic acid bonded to an amino-linker and so forth. In addition, there are also methods other than the above, such as utilization of a fluorescent group-containing carbodiimide compound which is highly reactive to nucleic acid bases (Japanese Patent Application Application Laid-open No. 10-287870).
However, among the aforementioned methods, the method described in Japanese Patent Application Laid-open No. 6-271599, the method utilizing biotin labeling and the method utilizing amino-linker bonding have drawbacks that it is not possible to introduce the fluorescent substance into naturally occurring nucleic acids, and the operations are complicated. The fluorescent group-containing carbodiimide compound exhibit good solubility in water because of the existence of quaternary ammonium salt in its molecular structure. However, in order to utilize a fluorescent substance with low solubility in water, such as a fluorescent substance having such a large electron system that it should have absorption in the near-infrared region, further improvement of the water solubility has been desired.